Foram estudados três grupos, o 1.º constituído por 8 pacientes normais (GI), o 2.º por 19 pacientes portadores de insuficiência cardíaca congestiva (G2) e o 3.º, por 28 pacientes portadores de cardiopatia isquêmica sem insuficiência cardíaca (G3), durante cateterismo cardíaco em situação basal e em apnéia inspiratória. Durante a inspiração, a pressão média no átrio direito aumentou de 2,0 ± 0,7 mmHg para 5,0 ± 1,8 mmHg (p 0. 05) in group II; from 3.0 ± 0.4 mmHg to 5.0 ± 1.3 mmHg (p > 0.05) in group III. Mean pulmonary pressure increased from 13.0 ± 1.1 mmHg to 18.0 ± 18 mmHg. (p < 0.05) in group I, did not change in group II and increased in group III from 18,0 ± 3.5 mmHg to 21.2 ± 1.9 mmHg (p < 0.05) in group III. Although left ventricular systolic pressure had a slight decrease in all groups, this decrease proved significant only in patients belonging to group III (p < 0,05). Left-ventricular end-diastolic pressure did not change in any group. The mean aortic pressure decreased from 98.0 ± 3.4 mmHg to 90.0 ± 3.2 mmHg (p < 0.05) in group II and from 114.0 ± 3.6 mmHg to 109.0 ± 3.6 mmHg (p < 0.05) in group III. The heart rate decreased from 80.0 ± 3.2 bpm t o 7 0 . 0 ± 2 . 8 b p m ( p < 0 , 0 1 ) in group I ; from 77.0 ± 3.7 to 70.0 ± 3.2 bpm (p < 0.01) in group II; from 77.0 ± 1,7 bpm to 71.0 ± 1.5 bpm (p < 0,001) in group III. The cardiac output decreased from 6.5 ± 0.3 l/mim to 5.6 ± 0.3 l/ min (p < 0.01) in group I; from 5.8 ± 0.3 1/min to 5.0 ± 0.3 l/ min (p < 0,01) in group II and from 5.7 ± 0.2 l/min to 5.0 ± 0.2 l/min (p < 0.001) in group III. The systolic volume did not change in any group
